The present invention relates to solar tracking devices designed for maintaining a solar energy collecting device in optimum position with respect to the sun.
Solar energy collectors such as thermal collection devices and solar cells for conversion of solar radiation to electrical energy operate most efficiently when aimed directly at the sun. For this reason numerous types of tracking devices have been developed to follow the sun from east to west each day and adjust also for seasonal changes in the sun's position. While many systems utilize clockwork motors and similar mechanically powered elements, one very simple type of system requiring no external power input is disclosed in U.S. Pat. No. 2,999,943 granted Sept. 12, 1961 to C. W. Geer. In this device a pair of closed containers interconnected in fluid communication are mounted on opposite sides of a pivot axis. The containers are partially filled with a low boiling point fluid and sun shielding means are positioned relative to the containers so that equal solar radiation reaches the containers only when the device is aimed directly at the sun. Otherwise one container receives more radiation than the other causing differential evaporation of the fluid and forcing fluid to the opposite container due to pressure differentials. The weight of the excess fluid on one side causes tipping until the device is aimed toward the sun. While the Geer patent does not specifically disclose it the system must maintain its center of gravity below the pivot axis to prevent tipping completely as soon as one container contains more liquid than the other.
The device of the Geer patent, however, follows the sun from east to west and then remains oriented overnight with the device aimed at the west. It must be either manually reset to the easterly direction during the night or await rising of the sun sufficiently high above the horizon in the morning so that the sun's rays reach over the high eastern shield and reach the western container to start causing vaporization. A substantial portion of morning sunlight therefore is lost before orientation is achieved.